microsd breakout seems to have specific pull-ups/pull-downs in the board

I will test with direct connection to microsd pins later.

This has been tested on an MK802 only, but should theoretically work for everything.

This has been confirmed working on an A13 Tablet as well.

Microsd

Pin

JTAG Connection

14-pin ARM JTAG Header

Data2

1

TCK

9

Cmd

3

TDO

11

Data0

7

TDI

5

Data1

8

TMS

7

VDD

4

VTG

1,13

GND

6

GND

2,3,4,6,8,10,12,14

It is important to make sure boot0/boot1/u-boot/kernel doesn't pinmux this away, so nothing else must be using the pins.
The script.bin needs to contain a correct jtag_para section. On my device, the default script.bin seems to contain an invalid configuration for the ports in question.
Below is the configuration matching the working JTAG!

I used a Dangerous Prototypes Bus Blaster V2(.5) for my experiments (http://dangerousprototypes.com/docs/Bus_Blaster).
I'm using the default buffer, which makes it jtagkey compatible.
For now, i've only verified that both UrJTAG and OpenOCD can detect a device over the JTAG connection, but I haven't managed to read/write from memory yet or anything else fancy.